Figure 1. (Top view) Free standing drilled-block manifold accepts three different valves; (Bottom view) Drilled metal-block manifolds with 1- and 1¼-in. ports accommodate high flows.
Some manifold manufacturers supply only manifolds; others provide manifolds that go only with their valves; still others supply manifolds and valves, but are willing to sell you their manifold and permit you to select valves of your choice. As more valves are built with standard mounting patterns, interchangeability becomes feasible for more and more systems.
Single-piece manifolds
These are available in two basic designs: laminar and drilled metal block.
Laminar design " In a laminar-type manifold, several layers of metal have appropriate passages machined or milled through them. These plates, usually steel, are stacked or sandwiched with the various fluid paths determined by the shape of the overlapping passages. Solid-metal end pieces are added, and the whole stack is brazed together.
Because the internal passages can be cut in contoured shapes and as large as necessary, nearly any flow rate can be accommodated with virtually no pressure drop. Because the stack is brazed together, these manifolds can handle pressures to 10,000 psi, and there is no limit to the number or size of the valves which can be mounted on the manifold.
Laminar manifolds are custom-designed. Valves and other connections can be located where appropriate for a specific application. But because of the permanently shaped flow passages and brazed construction, this type manifold cannot be modified easily if future circuit changes become necessary.
Drilled metal-block design " Drilled metal block manifolds, Figure 1, also can be custom-designed for specific applications. Usually made from a slab of steel, aluminum, or cast iron, the blocks are drilled to provide flow passages for design requirements. This network of drilled passages also enables you to locate valves as desired, with some limitations because the drilled passages must be straight.
Other drilled-block manifolds accept cartridge valves into cavities drilled into the manifold surface. Interconnecting flow passages travel through the manifold from the valve cavities. Some cartridge valves have threaded bodies that hold them in threaded cavities; others slip into smooth cavities where they are retained by plates on the manifold surface.
Modular manifolds